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The Use of the XGBoost and Kriging Methods in the Prediction of the Microstructure of CGI Cast Iron

Sztangret Łukasz, Olejarczyk-Wożeńska Izabela, Regulski Krzysztof, Gumienny Grzegorz, Mrzygłód Barbara

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 4

22--33

EN

Compacted Graphite Iron (CGI) is a unique casting material characterized by its graphite form and extensive matrix contact surface. This type of cast iron has a tendency towards direct ferritization and possesses a complex set of intriguing properties. The use of data mining methods in modern foundry material development facilitates the achievement of improved product quality parameters. When designing a new product, it is always necessary to have a comprehensive understanding of the influence of alloying elements on the microstructure and consequently on the properties of the analyzed material. Empirical studies allow for a qualitative assessment of the above-mentioned relationships, but it is the use of intelligent computational techniques that allows for the construction of an approximate model of the microstructure and, consequently, precise predictions. The formulated prognostic model supports technological decisions during the casting design phase and is considered as the first step in the selection of the appropriate material type.

2

Predicting the microstructure of compacted graphite iron using a fuzzy knowledge‑based system

Gumienny Grzegorz, Macioł Andrzej, Macioł Piotr

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e87, 2023

EN

One of the important engineering materials is compacted graphite iron (CGI). Obtaining an expected microstructure leading to desired material properties is relatively difficult. In this paper, we present an approach to predicting the microstructure with a fuzzy knowledge-based system. On the basis of the results of statistical analysis and expert knowledge, an original taxonomy of CGI casts was formulated. The procedure of data acquisition, specimen preparation, analysis procedure and microstructures obtained are presented. Methods for expert experience-supported knowledge extraction from experimental data, as well as methods for formalizing knowledge as fuzzy rules, are introduced. The proposed rulesets, the reasoning process, and exemplary results are provided. The verification results showed that, using our approach, it is possible to effectively predict the microstructure and properties of CGI casts even in the absence of sufficient data to use data-driven knowledge acquisition. On the basis of the results obtained, examples of possible applications of the developed approach are presented.

3

The Influence of Alloying Additions on High Temperature Interaction Between Molten Compacted Graphite Iron and Alumina

Sobczak N., Bacior M., Turalska P., Bruzda G., Homa M., Sobczak J. J.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 3

1227--1238

EN

High temperature behavior of three compacted graphite iron (CGi) alloys on polycrystalline aluminasubstrates (99.7%, porosity <3%) were examined by the sessile drop method combined with classical contact heating procedure in flowing Ar. High-speed high-resolution CCd camera was used for continuous recording of the CGi/Al2 O3 couples during melting alloy, heating to and holding the couples at the test temperature of 1450°C for 15 min and their subsequent cooling. The comparative studies were made with conventional CGi (in wt.%: 3.70 C, 2.30 Si, 0.44 Mn, 0.054 P, 0.017 Mg, 0.015 S) and two alloys additionally containing the same amounts of 0.25 Mo, 0.1 V, 0.045 Sn and 0.032 Sb with different concentrations of Mg + Cu additions, i.e. 0.01Mg + 0.33Cu and 0.02Mg + 0.83Cu. All three CGi alloys demonstrated non-wetting behavior on the Al2 O3 substrates while the contact angle values slightly decreased with increase of the Mg + Cu content in the alloy, i.e. 131° (unalloyed CGi), 130° (0.01Mg + 0.33Cu) and 125° (0.02Mg + 0.83Cu). Structural characterization of solidified couples by light microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy revealed: 1) heterogeneous nucleation of discontinuous graphite layer at the drop-side interfaces and on the surface of the drops; 2) reactively formed Mg-rich oxide layer at the substrate-side interface; 3) the formation of satellite droplets on the surface of the drops during their solidification; 4) degeneration of initially compacted graphite to lamellar graphite after remelting and subsequent solidification of the drops, particularly in their surface layer.

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The Effect of Manganese on the Crystallisation Process, Microstructure and Selected Properties of Compacted Graphite iron

Gumienny G., Kurowska B., Just P.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 4

1269--1275

EN

The paper presents the effect of manganese on the crystallization process, microstructure and selected properties: cast iron hardness as well as ferrite and pearlite microhardness. The compacted graphite was obtained by Inmold technology. The lack of significant effect on the temperature of the eutectic transformation was demonstrated. On the other hand, a significant reduction in the eutectoid transformation temperature with increasing manganese concentration has been shown. The effect of manganese on microstructure of cast iron with compacted graphite considering casting wall thickness was investigated and described. The nomograms describing the microstructure of compacted graphite iron versus manganese concentration were developed. The effect of manganese on the hardness of cast iron and microhardness of ferrite and pearlite were given.

5

Copper in Ausferritic Compacted Graphite Iron

Gumienny G., Kacprzyk B.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

162--166

EN

This paper shows how it is possible to obtain an ausferrite in compacted graphite iron (CGI) without heat treatment of castings. Vermicular graphite in cast iron was obtained using Inmold technology. Molybdenum was used as alloying additive at a concentration from 1.6 to 1.7% and copper at a concentration from 1 to 3%. It was shown that ausferrite could be obtained in CGI through the addition of molybdenum and copper in castings with a wall thickness of 3, 6, 12 and 24 mm. Thereby the expensive heat treatment of castings was eliminated. The investigation focuses on the influence of copper on the crystallization temperature of the graphite eutectic mixture in cast iron with the compacted graphite. It has been shown that copper increases the eutectic crystallization temperature in CGI. It presents how this element influences ausferrite microhardness as well as the hardness of the tested iron alloy. It has been shown that above-mentioned properties increases with increasing the copper concentration.

6

Nickel in Compacted Graphite Iron

Gumienny G., Kurowska B., Szymczak T., Gawroński J.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2A

657--662

EN

The paper presents results of the research work concerning effects of nickel concentration on the crystallization process, microstructure and selected properties of the compacted graphite iron. Compacted graphite in the cast iron was obtained with use of the Inmold process. The study has comprised the cast iron containing nickel up to concentration providing obtainment of austenitic microstructure of the matrix. The effect of the nickel on temperature of the eutectic crystallization was specified. It has been presented composition of the cast iron matrix in function of nickel concentration in a casting with wall thickness of 3 mm and 24 mm. Moreover, it has been presented conditions defining the possibility of obtaining an austenitic and martensitic compacted graphite iron. Effect of the nickel on hardness of the cast iron was described.

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Effect of Copper on the Crystallization Process, Microstructure and Selected Properties of CGI

Gumienny G., Kacprzyk B., Gawroński J.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 1

51--56

EN

The paper presents the results of the research on the effect of copper on the crystallization process, microstructure and selected properties of the compacted graphite iron. Compacted graphite in cast iron was obtained using Inmold process. The study involved the cast iron containing copper at a concentration up to approximately 4%. The effect of copper on the temperature of the eutectic crystallization as well as the temperature of start and finish of the austenite transformation was given. It has been shown that copper increases the maximum temperature of the eutectic transformation approximately by 5 oC per 1% Cu, and the temperature of the this transformation finish approximately by 8 o C per 1% Cu. This element decreases the temperature of the austenite transformation start approximately by 5 oC per 1% Cu, and the finish of this transformation approximately by 6oC per 1% Cu. It was found that in the microstructure of the compacted graphite iron containing about 3.8% Cu, there are still ferrite precipitations near the compacted graphite. The effect of copper on the hardness of cast iron and the pearlite microhardness was given. This stems from the high propensity to direct ferritization of this type of cast iron. It has been shown copper increases the hardness of compacted graphite iron both due to its pearlite forming action as well as because of the increase in the pearlite microhardness (up to approx. 3% Cu). The conducted studies have shown copper increases the hardness of the compacted graphite iron approximately by 35 HB per 1% Cu.

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Development of a manufacturing technology of compacted graphite iron castings from a cupola furnace

Bouska O., Heunisch J., Zadera A., Nedelova K., Kobersky F.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 1

125-129

EN

Compacted graphite iron, also known as vermicular cast iron or semiductile cast iron is a modern material, the production of which is increasing globaly. Recently this material has been very often used in automotive industry. This paper reviews some findigs gained during the development of the manufacturing technology of compacted graphite iron under the conditions in Slévárna Heunisch Brno, Ltd. The new technology assumes usage of cupola furnace for melting and is beeing developed for production of castings weighing up to 300 kilograms poured into bentonite sand moulds.